Most operating systems for personal computers and other general-purpose computers allow software applications to access internal and external sound devices through an audio subsystem. Typically, the operating systems and/or the applications are implemented such that a user can select one audio input device and one audio output device among multiple sound devices connected to the computer, e.g. through respective USB connections. While such implementations make it very easy for a user to interact with the applications, they also restrict the use of the applications and may e.g. hinder two persons from simultaneously listening with each their headset to the same music played from the computer.
Patent application EP 2 544 096 A1 discloses an apparatus that can connect a USB host in a computer with two or more USB devices, such as headsets or other audio devices. The apparatus may comprise a splitter that splits an audio signal received from the USB host into two or more audio signals and provides the latter to the respective audio devices. It may further comprise a mixer that mixes two or more audio signals received from respective audio devices and provides the mixed signal to the USB host. Since the apparatus comprises hardware, production costs are invoked, and the versatility of the apparatus is furthermore limited by design.
A so-called “virtual audio cable” (VAC) known from the prior art allows splitting and/or mixing audio signals by means of software only, such that the extra hardware cost can be avoided. Although the known VAC is more versatile than the hardware solution, there are still use cases involving multiple audio devices that the prior art cannot support.